Fluorescein-based fluorescent porous aromatic framework for Fe3+ detection with high sensitivity

Abstract

Detection of essential trace metal elements in human bodies is of great significance for disease diagnosis. Recently, the fluorescence sensing method has attracted extensive attention. In this work, we have synthesized a fluorescein-based porous aromatic framework (PAF) by post-modification. The material named PAF-5CF shows high sensitivity and selectivity for Fe³⁺ in either solid state or liquid phase in the form of fluorescence quenching. A series of fluorescence measurements have confirmed that PAF-5CF can detect Fe³⁺ with high sensitivity and the limit of detection concentration (LOD) of PAF-5CF is 3.8 × 10⁻⁵ mol L⁻¹. We demonstrated the fluorescence quenching mechanism by investigating the ultraviolet absorption spectrum, which explains that the specific fluorescence quenching response to Fe³⁺ is an absorption competition quenching (ACQ) mechanism. This work provides a simple and highly sensitive method for detecting Fe³⁺ based on chemically stable PAFs, which promotes the practical application of Fe³⁺ detection.